Northwest Airlines flight 346
Northwest Airlines flight 346 was''' 'a Boeing 747-400 was a flight from Minneapolis-St. Paul Int'l Airport to Amsterdam-Schiphol Airport that crashed into an apartment complex just upon takeoff on November 15, 2007. A total of 260 people were killed (all 217 passengers and crew on board the flight and 43 people on the ground). Aircraft The aircraft involved was a Boeing 747-400 (registration number ''N661US). It was first delivered to Northwest Airlines on March 21, 1989 and had been operated continuously by the airline since that date. Accident Flight 346 departed from John F. Kennedy International Airport at approximately 4:30 pm with 503 passengers and 14 crew members aboard. After the plane had been flying for approximately 4 hours, 22 minutes, 7 seconds, and was passing from 35,000 feet the flight crew heard a loud "thump" which shook the aircraft. One and a half seconds later, the forward cargo door blew out. The door swung out with such force that it passed its normal stop and slammed into the side of the fuselage, bursting the fuselage open causing an explosive decompression. Pressure differentials and aerodynamic forces caused the cabin floor to cave in, and ten seats were ejected from the cabin as well as 10 passengers. The debris ejected from the airplane during the explosive decompression caused severe damage to the Number 3 and 4 engines, causing visible fires in both. When the door blew off, the floor had collapsed it severed all hydraulics. The loss of control of these key components meant that the pilots lost control of the aircraft entirely. The aircraft almost immediately attained a 20-degree, nose-down attitude, and started picking up speed but due to the aircraft falling too far it was too late. At a speed in excess of 507 miles per hour the plane slammed into an apartment complex in Detroit vertically exploding and disintegrating causing an intense inferno, instantly killing all 517 people on board Flight 346 as well as 43 people on the ground. Passengers and Crew Investigation The National Transportation Safety Board immediately commenced an investigation into the accident. The front cargo door as well as the ten rows of seats and the ten passengers was found in a trailer park 3 days. Unlike a plug door which opens inward and jams against its frame as the pressure outside drops (making it impossible to accidentally open at high altitude), the Boeing 747 was designed with an outward-hinging door. While this increases the cargo capacity, it requires a strong locking mechanism to keep the door closed. Deficiencies in the design of wide-body aircraft cargo doors were already known since the early 1970s from flaws in the DC-10 cargo door. Flight 346 had air vents since it was built but the force was so strong the vents failed and about two of them were sucked out when the door blew off. In its superseding report, the NTSB determined that the cause of the accident was the sudden opening of the cargo door, which was attributed to improper wiring and deficiencies in the door's design. It appeared in this case that a short circuit in the aging plane caused an uncommanded rotation of the latch cams, which forced the weak locking sectors to distort and allow the rotation, thus enabling the pressure differential and aerodynamic forces to blow the door off the fuselage, ripping away the hinge fixing structure, the cabin floor and side fuselage skin, causing the massive explosive decompression. This greatly contrasted with Flight 346, where all of the underfloor cables were severed in the decompression, and the pilots lost all control of their plane.An inspection of the door's electrical wiring discovered insulation breaches, and isolating certain electrical wires allowed the door to operate normally again.The lock sectors, latch cams, and latch pins on the door were inspected, and did not show signs of damage of the type predicted by the NTSB's original hypothesis Aftermath Category:Accident Category:50+ Fatalities